Skymet weather

Monsoon Forecast : Reading Too Much Between The Lines

April 12, 2023 6:22 PM |

Following one of our interview with magazine 'The Week' in June 2016, the author described the monsoon as seasonal but emotional event. Everything is hinged on these rains, from economic growth to political future and spiritual well being. Monsoon was described as a moody lover which can make an anxious nation wait while it decides to delay its arrival.  Sometimes, it may arrive with military punctuality, but then, whimsically decide not to empty its clouds over the landmass, leaving behind parched fields. At times, it moves at a languid pace, and on other occasions, charge with mindless fury. Despite all the science, time, money and mind  devoted towards forecasting, decoding monsoon remains a big challenge.  Uncertainty of its track and unpredictability of  behaviour remain the hallmark of this beautiful symphony. 

The monsoon is not the simple resultant of land heating up during summer, creating a low pressure in to which rain laden clouds rush in from the sea. It is a rather complex feature and almost every geographical event on earth has an impact on the monsoon's behaviour.  Winter snow in Eurasia, Himalayan snow, changes in Arctic ice, surface temperatures over Pacific waters, strengthening of warm currents like El Nino and a myriad other events play a decisive role.  

Earlier, there was little reluctance in announcing a bad forecast and plunging the country in to despair, even before first  drop of rain falls. It was prudent to couch the bad news in such comforting terms that only the discerning understood its real import.  With better models and capacity building, not only has forecasting got refined, but India, too, has developed resilience to ensure food security. 

Skymet  released its monsoon forecast 2023 on 10th April, announcing it to be below normal with seasonal rainfall 94% of its long period average (LPA) of 868.6mm.  The next day, 11th April,  India Meteorological Department also proclaimed the seasonal forecast stating it to be normal with rainfall of 96% of LPA. Both the forecast have model error of +/- 5%. Skymet forecast is on the higher end of 'below normal' and IMD forecast is on the lowest end of 'normal'. The difference between the two amounts to a rainfall of 18mm for the 4 month long session, which is otherwise just 2 days of rainfall in the core monsoon months of the season.  There can hardly be any better consensus on the monsoon forecast between any two independent weather agencies. Hitting bulls eye and issuing absolutely matching forecast is just not possible. Cards will open only at the end of the season to ascertain monsoon status, Normal-Below Normal-Above Normal or otherwise.

Both agencies have gone for a weaker monsoon, ostensibly on account of evolving El Nino in the Pacific Ocean during the season. Too much is being read in between the lines, without any conclusive evidence, specially by those who have least idea about the complexity of monsoon.  Monsoon table for the last 5 years is being shared without authenticity, to arrive at ' hits and misses'  of two weather agencies. For the benefit of readers, IMD issues 3 forecasts ( mid April, end of May,  end of July/start of August) to cover the monsoon season. Skymet comprehensively releases mostly one or at best the second one, mid way through the season to apply course correction, if needed. 

Rainfall Predictions: 2017-2022 (% LPA)

Monsoon 2023 is likely to proceed under the shadow of El Nino.  Indian Ocean Dipole will be +VE neutral to start with and gain amplitude till halfway through the season to become 'low moderate'. Model projections indicate that the index will have a tendency to turn neutral again toward 2nd half of the season.


Since the year 2000, there have been six El Nino or evolving /devolving El Nino years : 2002, 2004, 2009, 2014, 2015 and 2018.  Five of these ended in a drought, with 2 of them 'severe drought' in 2002 and 2009. Sixth and the last in 2018 narrowly averted drought and ended with 90.6% rainfall of LPA. Scare of El Nino this year is real and the 2nd half of the season is likely to be impacted strongly.  Fingers crossed but monsoon 2023 is unlikely to be without suspence and thrill.  

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